To examine the effects of non-nutritive sweetener consumption on appetite and food intake in humans and animal models and the potential mechanisms responsible.

Inclusion Criteria:

None identified.

Exclusion Criteria:

None identified.

Description of Study Protocol:

Statistical Analysis

None used.

Data Collection Summary:

Timing of Measurements

None identified.

Dependent Variables

BMI

Appetite

Food intake.

Independent Variables

Non-nutritive sweetener (NNS) ingestion

Nutritive (NS) ingestion.

Description of Actual Data Sample:

Initial N

Several dozen studies were referenced in this narrative review but no exact number was given, nor were there any tables displaying a summary of data or findings.

Summary of Results:

Consumption Levels of NNS and Association between Consumption of NNS and Appetite, Energy Intake and BMI

Topic

Primary Findings

Consumption levels of NNS

Since manufacturers are not required to provide content information, there is no direct measurement of use

From 2003 to 2004, 15.1% of the American population reported that they consumed foods or beverages containing NNS

Consumption of NNS is increasing. In the American population, from 1998 to 2004, there was a 6.9% increase in NNS beverage consumption and an 81.2% increase in consumption of foods with NNS. Amount of NNS consumption has increased 37.7% and 14.2%, respectively.

NNS and appetite

Earlier reviews report that acute exposure to NNS via non-energy-yielding vehicles augments hunger and that the sweetness of NNS enhances post-ingestive hunger. This has been found to be true of sodium chloride as well and now it is believed that, in general, oral exposure to a palatable stimulus in the absence of energy increases hunger.

NNS have no effect on hunger when administered via nasogastric tube or capsules, indicating that changes in hunger may be due to orosensory stimulation. It is unclear if this translates to increased energy intake.

When NNS are incorporated into energy-yielding foods or are part of a meal, no increase in hunger is evident.

NNS and energy intake

It has been hypothesized that carbohydrate replacement (not addition) with NNS results in a relative increase in fat and protein consumption. However, in free-living individuals NNS are used as additions to the diet and not substitutions as evidenced by overall increased contribution of carbohydrate in the diet (as a percent of energy intake).

The majority of evidence indicates that NNS have no short-term effects on energy intake

Longer-term feeding trials generally indicate that the use of NNS result in no change or a reduction in energy intake (incomplete compensation).

NNS and BMI

Intervention trials fail to document that NNS promote weight gain

Observational studies are equivocal. Some studies show increased risk of weight gain associated with increased consumption of NNS, while others show that consumption of NNS facilitates weight management in individuals who have previously lost weight.

There are many methodological differences amongst various studies, thereby confounding results and making comparisons among studies difficult.

Mechanisms of NNS and weight management

NNS serve to maintain palatability of foods that are low in energy

No data indicate that NNS modify energy balance independently of their influence on energy intake

NNS, when substituted for NS, results in decreased carbohydrate intake; however most NNS are additions to the diet and not substitutions.

Mechanisms of NNS and appetite stimulation

Cephalic phase stimulation: Neurally mediated physiological responses to prime the body to optimize digestion. Researchers disagree as to how cephalic stimulation affects hunger. The role of NNS is unclear and supportive evidence that NNS increase hunger via this mechanism is unsubstantiated.

Nutritive and osmotic effects: Changes in the osmotic and nutrient properties of foods and beverages through substitution of NNS for NS has not been shown to affect satiety

Gut peptide response: Failure of NNS to release peptides that augment satiety may result in increased energy intake; however, some NNS elicit the release of satiety peptides (sucralose) while others (aspartame) do not

Palatability: NNS increase palatability which may result in over-consumption. Additionally these foods may be viewed as “healthy” and over-consumption may occur; however, there is inconclusive evidence that palatability influences absolute energy intake.

Theoretical mechanisms by which NNS may enhance energy intake or balance

Loss of signal fidelity

Activation of reward systems

Training the palate to like sweetness

None of these theories have been satisfactorily evaluated and no substantial evidence exists to support that NNS increases energy intake in free-living individuals.

Author Conclusion:

The safety of NNS has been established but their influence on appetite, energy intake and body weight has not been fully characterized

Recent studies show that when incorporated into energy-containing foods NNS do not cause an increase in hunger

Longer-term feeding studies show an incomplete compensation of energy of 5% to 15% when replacing NS with NNS; however, clear evidence of improved weight maintenance in free living individuals is still lacking

NNS have been thought to exacerbate the problem of positive energy balance; however, none of the mechanisms by which NNS may do so have been adequately substantiated by available evidence

There is emerging evidence that selected NNS may stimulate the release of satiety hormones

Use of NNS likely promotes a preference for higher sweetener levels of foods and beverages, but it is unclear if this leads to increased energy intake

When used as substitutes for NS, not additions to the diet, NNS have the potential to aid in weight management, but it is unclear if they are used in this way

More studies in free-living populations are warranted to clarify NNS patterns of use.

Funding Source:

Other:

None (review)

Reviewer Comments:

This review is comprehensive and interesting to read; however, it is highly ambiguous and makes no conclusive statements regarding the topic. There is no table to summarize reviewed research results.

Quality Criteria Checklist: Review Articles

Relevance Questions

1.

Will the answer if true, have a direct bearing on the health of patients?

Yes

2.

Is the outcome or topic something that patients/clients/population groups would care about?

Yes

3.

Is the problem addressed in the review one that is relevant to dietetics practice?

Yes

4.

Will the information, if true, require a change in practice?

Yes

Validity Questions

1.

Was the question for the review clearly focused and appropriate?

Yes

2.

Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described?

No

3.

Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased?

No

4.

Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible?

Yes

5.

Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined?

Yes

6.

Was the outcome of interest clearly indicated? Were other potential harms and benefits considered?

Yes

7.

Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described?